Table 1.
Comparison According to Graft Positiona.
| Whole group (n = 92) | Anterior group (n = 73) | Center group (n = 19) | P | |
|---|---|---|---|---|
| Age (years) | 48.7 ± 10.6 | 48.2 ± 10.3 | 48.1 ± 10.4 | .968 |
| Sex (male/female) | 59/33 | 44/29 | 15/4 | .181 |
| Body mass index | 25.0 ± 2.84 | 24.6 ± 2.91 | 25.6 ± 3.1 | .078 |
| Operation segments | ||||
| C3-C4 | 6 | 4 | 2 | |
| C4-C5 | 14 | 13 | 1 | |
| C5-C6 | 47 | 37 | 10 | |
| C6-C7 | 25 | 19 | 6 | .709 |
| Plate/graft/screw type | ||||
| Skyline/FDBA/Fixed+Variableb | 55 | 46 | 9 | |
| Atlantis/Machined/Fixedc | 37 | 27 | 10 | .215 |
| Preoperative radiologic parameters | ||||
| C2-C7 angle (°) | 7.09 ± 12.78 | 8.01 ± 12.37 | 3.53 ± 14.04 | .235 |
| Segmental angled (°) | 4.42 ± 8.16 | 4.93 ± 7.91 | 2.47 ± 8.97 | .403 |
| Segmental height (mm) | 34.43 ± 3.19 | 34.21 ± 3.22 | 35.27 ± 2.97 | .197 |
| Postoperative radiologic parameters | ||||
| 1 week | ||||
| C2-C7 angle (°) | 9.05 ± 9.29 | 9.68 ± 9.10 | 6.59 ± 9.84 | .197 |
| Segmental angled (°) | 5.99 ± 7.23 | 6.45 ± 7.14 | 4.37 ± 6.29 | .251 |
| Segmental height (mm) | 36.36 ± 2.99 | 36.19 ± 3.05 | 36.99 ± 2.75 | .302 |
| Graft/endplate ratioe | 74.5 ± 10.6% | 75.9 ± 11.0% | 69.0 ± 6.58% | .01 |
| 1 year | ||||
| C2-C7 angle (°) | 9.31 ± 10.22 | 10.01 ± 10.37 | 6.60 ± 9.38 | .175 |
| Segmental angled (°) | 5.57 ± 7.28 | 5.99 ± 7.23 | 3.95 ± 7.43 | .406 |
| Segmental height (mm) | 35.20 ± 2.95 | 35.18 ± 2.92 | 35.31 ± 3.12 | .857 |
| Subsidencef | 15 (16%) | 8 (11%) | 7 (39%) | .012 |
| Pseudarthrosis | 13 (14%) | 10 (14%) | 3 (15%) | .727 |
| Clinical result | ||||
| Preoperative VAS | 5.77 ± 1.85 | 5.64 ± 1.84 | 6.26 ± 1.82 | .123 |
| Postoperative 1-year VAS | 2.27 ± 1.65 | 2.30 ± 1.71 | 2.16 ± 1.42 | .67 |
| Preoperative NDI | 30.74 ± 5.63 | 30.55 ± 5.54 | 31.47 ± 6.50 | .322 |
| Postoperative 1-year NDI | 18.00 ± 4.22 | 18.29 ± 4.21 | 16.89 ± 4.15 | .205 |
Abbreviations: FDBA, freeze-dried bone allograft; VAS, Visual Analogue Scale; NDI, Neck Disability Index.
a Descriptive data represents mean ± standard deviation. Boldface indicate that the number is statistically significant, p<0.05.
b Skyline anterior cervical plate (manufactured by Dupuy) with FDBA, freeze-dried bone allograft, fixed with fixed-angle type screws at the top of the fusion level and variable-angle type screws at the bottom.
c Atlantis anterior cervical plate (manufactured by Medtronic) with machined structural allograft spacer, fixed with fixed-angle type screws.
d Segmental angle is the angle formed by the lines drawn parallel to the superior margin of the upper vertebral body and the inferior margin of the lower vertebral body of the treated level.
e Graft/endplate ratio is defined as graft length divided by endplate length.
f Subsidence is defined segmental vertebral body height decreased by more than 2 mm at 1 year after surgery than at 1 week after surgery.